Cumulative Frequency

Question 1

How do you make a cumulative frequency column?

Answer 1

Add the frequencies together as you move down the frequency table

Question 2

How do you plot a Cumulative Frequency Graph?

Answer 2

Plot the upper class limit against the cumulative frequency
Join the points with a straight line.

Question 3

How do you find the Median from a c.f. graph?

Answer 3

Find the total frequency.
Divide by two.
Draw a line across at this point.
Read the value on the x-axis.

Question 4

How do you find the IQR from a cumulative frequency graph?

Answer 4

Read the c.f. graph at the Upper quartile and the Lower quartile (of the total frequencies).
IQR = UQ - LQ

Question 5

How do you find how many people were higher than a given amount?

Answer 5

Find the given amount on the x-axis.
Draw a line up at this point.
Read the cumulative frequency.
Subtract this amount off the total frequency.